Wireless communication devices such as cellular phones and tablets can be charged from an electrical power outlet. There are a number of issues relating to charging these devices, for example, the battery charging time can be lengthy and charging current for large size batteries (e.g., above 3-4 AH), which require more power, exceeds maximum rated current (e.g., 2 A) through a connection cable. Existing chargers do not allow the communication device operation without the battery being connected or without depleting battery charge while using the communication device with heavy load use cases. Further, charging efficiency is not optimized, which can result in undesired heat generation while charging the device.
A charger apparatus is also desired to allow linear charging by tracking battery voltage. While universal serial bus (USB) standard specifies charger type and method of recognition through reading voltage/impedance on USB D+/D− pins, original equipment manufacturers (OEMs) tend to add new resistance identification (RID) value and/or method of detection. For example, some vendor's adapters use battery charging detection scheme based on sensing and measuring USB D+/D− pins using analog or digital comparators for every charger type. USB standard has developed USB power delivery (PD), but its implementation can be costly for applications such as phone applications.